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Using MHTC 96 Setaram high temperature drop calorimeter, partial and integral enthalpies of mixing of liquid alloys were determined in the Ag–Ga, Cu–Ga and in the ternary Ag–Cu–Ga system. The ternary alloys were investigated along two cross-sections at two different temperatures: 1128K and 1273K, respectively. Experimental data were used to find ternary interaction parameters by applying the Redlich–Kister–Muggianu...
In the present work, the surface tension of liquid Si and Ge has been measured by the pendant/sessile drop combined method over the temperature range of 1723–1908K and 1233–1313K, respectively. The new surface tension data, the molar volumes and the melting temperatures of silicon and germanium as well as the excess Gibbs energy data of the Ge–Si liquid phase are the inputs for Calphad type modelling...
Phase equilibria of the quaternary Gd–Ti–Al–Cu system have been studied with particular respect to solidification and phase separation phenomena in metallic glasses. Along the section Gd55−xTixAl25Cu20 the primary solidifying phase changes from Gd2CuAl (x=0) toward α-Ti (x≥10) with rising Ti-fraction x. This is accompanied by an upturn of the liquidus temperature from TL=745°C to TL>1100°C. The...
Cadmium vapor pressures were determined over Ce–Cd samples by an isopiestic method. The measurements were carried out in the temperature range from 690 to 1080K and over a composition range of 48–85at% Cd. From the vapor pressures thermodynamic activities of Cd were derived for all samples at their respective sample temperatures, and partial molar enthalpies of Cd were obtained from the temperature...
The melting behavior of ß-boron at the boron-rich side of the B–C binary phase diagram is a long standing question whether eutectic or peritectic. Floating zone experiments have been employed to determine the melting type on a series of C-containing feed-rods prepared by powder metallurgy and sinter techniques. Melting point data as a function of carbon-content clearly yielded a peritectic reaction...
The Ag–Bi–Cu system is one of the ternary alloy systems that until now is not fully experimentally studied. The literature survey indicated that the experimental data on this system are scarce. In this study the DTA method was employed to study phase transitions with temperature in Ag–Bi–Cu alloys. The measurements were performed on samples of constant silver to bismuth mole fraction ratio 4:1, 1:1,...
Melting in the La2O3–Y2O3–Al2O3 system was investigated using high temperature DTA and microstructures were studied by electron microscopy (SEM/EDX). The experimental results are consistent with calculations based on liquid phase description without ternary interactions and solid phases with limited mutual solubility of La and Y. The thermodynamic description was used to calculate vertical sections...
Literature data about phase equilibria and thermodynamics of the Co–Ni, Co–Ti, Ni–Ti and Co–Ni–Ti systems have been reviewed and critically assessed. Co–Ni–Ti phase equilibria are not completely known and contradictory results have been reported, especially about existence, stability range and phase relations of the Ti(Co,Ni)3 ternary phase in the region at x(Ti)<0.5. Then the 900°C isothermal...
One of the key issues in the development of iron aluminides is the thermodynamic modeling of alloying effects on the long-range and short-range order states of the underlying bcc phase, needed for the proper description of their effects upon phase equilibria and physical properties of multicomponent alloys. The present work describes results obtained by the present research group in the development...
CALPHAD approach is very useful in predicting the change of phase diagram of a nanoparticle system from a bulk system. However, the CALPHAD-type thermodynamic descriptions for nanoparticles have not been generalized, yet. The present paper suggests the generalized equations to describe thermodynamic variables for nanoparticles. With the proposed general equations, thermodynamic properties of Ag–Au...
Self-consistent thermodynamic descriptions of the Mg–Zn and Fe–Si systems have been obtained based on data available in the literature. This involved modification of the description of liquid phase in order to remove the ‘unlikely’ miscibility gap that appears in calculations when using data from earlier thermodynamic assessments. The results calculated using current descriptions are in good agreement...
In this paper the performance of the linear, exponential and combined models to describe the temperature dependence of the excess Gibbs energy of solutions in the framework of the Redlich–Kister model is discussed. The models are not compared to existing Calphad optimized databases, rather they are tested against the 209 binary solid and liquid metallic alloys, for which reliable experimental data...
The paper focuses on the thermochemical behaviour of the binary Sm–Mg alloys. The enthalpies of formation of the Sm–Mg intermetallic compounds have been determined at 300K by high temperature direct synthesis calorimetry. The following results in kJ/mole of atoms are reported: −18.5±2 (SmMg), −16.0±2 (SmMg2), −12.0±2 (SmMg3), −8.5±2 (SmMg5) and −5.5±2 (Sm5Mg41). The results are compared with the earlier...
We investigated the evolution of 6–130nm silver thin films during vacuum annealing. The bimodal character of cluster size distribution was observed for 12–130nm films. One average cluster size is 40–80nm, other average size is 380–420nm. At the same time it is shown that two simultaneous processes occur: coalescence and evaporation. The bimodality distribution character is associated with these two...
On the basis of the knowledge on electronic part of melting entropy, there was proposed a new method to estimate the effective mass of conducting electrons (mn⁎) in the semiconductors melts. On the example of the AIIISb compounds there is shown that melting according to the type semiconductor–metal is accompanied by a sharp increase of the mn⁎ value. This suggests huge changes in energy spectrum of...
V–Zr is a well known system where a phase transformation from rhombohedral V2Zr structure to cubic C15 Laves phase occurs during heating at about 115K. Here we provide a thermodynamic description of this phenomenon, supported by ab initio calculations. We utilize our new method of extension of the Scientific Group Thermodata Europe (SGTE) unary thermodynamic database to zero Kelvin and demonstrate...
The aluminum diffusion in aluminide coatings deposited on nickel by the CVD method was investigated. The microstructure, chemical and phase compositions of coatings were examined by SEM, EDS and XRD techniques. The triple zone structure was revealed. The β-NiAl phase was on the surface of the coatings, whereas γ-(Ni) and γ′-Ni3Al formed deeper parts of the coatings. Diffusion coefficients were calculated...
The comparative analysis of experimental and calculated viscosity of binary alloys was performed applying models in which enthalpy or free enthalpy of mixing change is combined with the viscosity of components. Some models incorporate also densities, molar volumes of alloys or atomic radius of metals but the present considerations focused only on thermodynamic functions. The considerable discrepancies...
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